Mini-gastrin analogue, in particular for use in CCK2 receptor positive tumour diagnosis and/or treatment

Abstract

A gastrin analogue shows high uptake in CCK-2 receptor positive tumors and simultaneously a very low accumulation in the kidneys. This is achieved by a mini-gastrin analogue PP-F11 having the formula: PP-F11-X-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Y-Asp-Phe-NH.sub.2, wherein Y is an amino acid replacing methionine and X is a chemical group attached to the peptide for diagnostic and/or therapeutic intervention at CCK-2 receptor relevant diseases. Very suitable compounds with respect to a high tumor to kidney ratio are mini-gastrin analogues with six D-glutamic acids or six glutamines. These compounds still possess a methionine which can be oxidized easily which is a disadvantage for clinical application under GMP due to the forms which may occur. The elimination of the methionine leads to a lower affinity to oxidation which in general favors the tumor-kidney-ratio. Ideally, the methionine is replaced by norleucine. This PP-F11N mini gastrin exhibits currently the best tumor-kidney-ratio and is the most promising candidate.

Claims

1. A method of treating CCK-2 receptor associated diseases in a subject in need thereof, wherein the method comprises the step of administering a mini-gastrin analogue having the formula: X-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Y-Asp-Phe-NH.sub.2, wherein Y is an amino acid replacing methionine and X is a chemical group attached to the peptide for the purpose of therapeutic intervention at CCK-2 receptor associated diseases, to the subject, and wherein the CCK-2 receptor associated disease is selected from CCK-2 receptor positive tumors.

2. The method according to claim 1, wherein the CCK-2 receptor positive tumor is selected from medullary thyroid carcinomas (MTC), small cell lung cancers (SCLC), astrocytomes and stromal ovarial tumors.

3. The method according to claim 1, wherein Y is a methionine isosteric amino acid with no oxidation potential.

4. The method according to claim 1, wherein Y is norleucine.

5. The method according to claim 1 or 4, wherein X is a chelator for radiometals complexed with a radionuclide.

6. The method according to claim 5, wherein the chelator for radiometals is DOTA.

7. The method according to claim 5, wherein the radionuclide is selected from the group consisting of .sup.177Lu, .sup.90Y and .sup.111In.

8. The method according to claim 1 or 2, wherein the mini-gastrin analogue is: DOTA-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH.sub.2.

9. The method according to claim 8, wherein the DOTA-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH.sub.2 is labelled with .sup.177Lu.

10. The method according to claim 1, wherein X is an optically active chemical compound.

11. The method according to claim 1, wherein X is a chemotherapeutic active compound.

12. The method according to claim 1, wherein X is a nanoparticle or a liposome which has a therapeutic function by itself or which is loaded with an active compound.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Preferred embodiments of the present invention are hereinafter described in more detail with respect to the attached drawings which depict in:

(2) FIG. 1 the structural design of PP-F11N starting from a mini-gastrin analogue PP-F11 being arised from the COST initiative;

(3) FIG. 2 the biodistribution of PP-F11, PP-F11N and PP-F11 ox (oxidized PP-F11) after four hours in the CD1 nu/nu mice model;

(4) FIG. 3 the bio diversion of PP-F10, PP-F10N and PP-F10 ox (oxidized PP-F10) after four hours in the CD1 nu/nu mice model; and

(5) FIG. 4 the stability of diverse mini-gastrin analogues with the course of the time.

DESCRIPTION OF THE INVENTION

(6) FIG. 1 illustrates the mini-gastrin analogue PP-Flu that has been derived from the COST initiative mentioned above. The modified mini-gastrin analogue PP-F11N has been achieved by the exchange of the oxidizable amino acid methionine with norleucin. DOTA stands for 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid which is an organic compound with the formula (CH.sub.2CH.sub.2NCH.sub.2CO.sub.2H).sub.4. The molecule consists of a central 12-membered tetraaza (i.e., containing four nitrogen atoms) ring. DOTA is used as a complexing agent, especially for lanthanide ions. Its complexes have medical applications as contrast agents and cancer treatments.

(7) PP-F11N has been investigated according to the CD1 nu/nu mice model. As compared to PP-F11, the mini-gastrin analogue PP-F11N exhibited a significant higher tumor uptake which also leads to a very favorable tumor-noise ratio with very few accumulation in the kidneys. FIG. 2 illustrates the biodistribution of PP-F11, PP-F11N and oxidized PP-F11 ox (oxidized PP-F11) after 4 hours in the athymic CD1 nu/nu mice model. Tumour positive: with human CCK-2 receptor transfected A431 cells on one side of the mouse; tumor negative: CCK-2 receptor negative A431 cells on the other side of the mouse. The effect of the higher tumor uptake by the exchange of methionine with norleucine is specifically apparent with compounds having the DGlu6 sequence, different from compounds having a sequence with DGLn6 which is referred to as PP-F10.

(8) FIG. 3 shows the results for PP-F10 and PP-F10N and PP-F10 ox (oxidized PP-F10) in comparison to the results shown in FIG. 2. The structural formula of the PP-F10's is given below:

(9) PP-F10: DOTA-DGln-DGln-DGln-DGln-DGln-DGln-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH.sub.2

(10) PP-F10N: DOTA-DGln-DGln-DGln-DGln-DGln-DGln-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH.sub.2;

(11) PP-F10 ox: DOTA-DGln-DGln-DGln-DGln-DGln-DGln-Ala-Tyr-Gly-Trp-Met(ox)-Asp-Phe-NH.sub.2.

(12) A promising tumor uptake can therefore not be seen in FIG. 3 since other organs, such as the pancreas, the kidney and the bones take partially even higher doses than the targeted tumor.

(13) FIG. 4 illustrates the pharmacologic stability of PP-F11N as compared to PP-F11, PP-F10N and PP-F10 (all radio-labelled with .sup.177Lu. The stability has been checked in human serum; the measurements of the metabolites have been executed by means of HPLC. The mini-gastrin analogue PP-F11N according to the present invention shows the highest pharmacologic stability of all probands.

(14) Materials: The peptides (PP-F10, PP-F10N, PP-F11 and PP-11N) were synthesized by PLS (Heidelberg, Germany) by the Merrifield method. All the chemicals were purchased from Sigma-Aldrich (Buchs, Switzerland). A431 cells (cell line squamous cell carcinoma) were stably transfected with cDNA encoding for CCK2R or with empty vector (mock-transfected).sup.1 and were a kind gift from L. Aloj (Naples). Lu-177 was purchased from ITG (Germany, Munich). The peptide conjugates were complexed with natural .sup.natLu.

(15) The labeling of the mini-gastrins has been executed under the following circumstances:

(16) System for HPLC analysis:

(17) System: Pump Varian Prostar 2030.01, Diode Array 330.71, Autosampler 410, Packard Radiomatic Flow-One\

(18) Column: Stability 120 BS-C23 3 m 150*4.6 mm, Dr. Maisch Gradient:

(19) TABLE-US-00001 % H2O + 0.1% % ACN + 0.1% Min TFA TFA 0 90 10 3 90 10 15 5 95

(20) System for the purification:

(21) Pump 1: Waters 515, Pump 2: Hitachi L-7000, Knauer UV Detector K2510, Radio-Monitor Eberline, interface SS420X, EZstart

(22) Rheodyne Manuel Injector

(23) Column 1: Stability 120 BS-C23 3 m 10*4.6 mm, Dr. Maisch

(24) Column 2: Stability 120 BS-C23 3 m 150*4.6 mm, Dr. Maisch

(25) TABLE-US-00002 % H2O + 0.1% % ACN + 0.1% Min TFA TFA Valve 1 Valve2 0 72 28 Inject Load 3 72 28 Inject Inject 20 60 40 25 5 95 35 5 95

(26) Products:

(27) Lu-177: lot Lu-12-052-01/121042, Activity 2 GBg/200 l 0.04M HCL, itg (ITM AG)

(28) PP-F11N: 0.25 mM H.sub.2O solution

(29) Ammonium solution: Sigma-Aldrich metal free

(30) Na Ascorbate: Sigma-Aldrich

(31) HCl 30%: sigma-Aldrich nmetal free

(32) H.sub.2O: from Milipore system Biotel

(33) Labelling of the peptide PPF11N with Lu-177:

(34) The Labelling of Lu-177 with the PPF-11N was made with an isotope:peptide ratio of 1:47.

(35) Mixture of Lu-177 with peptide to an eppendorf 1.5 ml lw binding: 20 l Lu-177 (190 MBq) 5 l Ammonium ascorbate 0.7M 50 l PPF-11N 0.25 mM 5 l HCl 0.04M

(36) The mixture was heated for 20 minutes at 95 C.

(37) Afterwards the complex was purified and checked with HPLC methods.

(38) Two syntheses were achieved in parallel Purification of labelling peptide with HPLC

(39) The two labellings reaction was injected into a 2 D HPLC. Description of 2D HPLC: First step: inject the product into the loop with a rheodyne manual injector and push the product with a first pump through the column 1. The product is transferred from loap to the column 1 and is washed with H.sub.2O+0.1TFA. Second Step: start the gradient with a second pump and change the position of the valve to connect in serial the column 1 and column 2. The product is push from column 1 in column 2. The excess of peptide is separed of the labeled Lu-177-PPF11N in the column 2 and is collected with a fraction size of 500 ul. The collected tube contains still 5 mg Na-ascorbate. Result of purification with HPLC

(40) TABLE-US-00003 Activity Collection [MBq] % time [min] Volume [l] Injected 378 100 80 activity Remainder 30 8 eppendorf tube Fraction 3 120 31 12.5-13.0 500 Fraction 4 180 48 13.0-13.5 500

(41) Preparation of the labeled peptid for mouse i.v. injection

(42) The two fractions have been fused and the solvent was evaporated during 35 min.

(43) Afterwards 600 ul PBS 1 with 10 ul 5 mM DTPA solution was added.

(44) Final solution: 295 MBq/610 ul.

(45) Stability

(46) 12 MBq of the radiolabelled compound was incubated in 2 mL fresh human plasma. A 40 L probe was taken after 0, 1, 2, 18, 24, 48 and 72 h and added 200 L (50% Methanol and 50% Acetonitril) in a Mini-UniPrep Filter. The solution is filtered after vortexing. 40 L of the filtered solution is analyzed by HPLC.

(47) Biodistribution Studies

(48) CD1 nu/nu mice were injected with 510.sup.6 A431 cells. CCK-2 receptor positive A431 cells' were injected into one flank and mock cells on the other as an unspecific control. The tumors reach a weight of about 80 to 120 mg after about 10 days. 150-200 kBq (5 pmol) of the radiolabelled peptides were injected into the tail vein. Mice were killed by CO.sub.2 asphyxiation after defined time points post injection. The organs were dissected, weighted and the activity was measured. The % injected activity per gram (% i.A./g) was calculated. The animal experiments were approved by the local animal welfare committee and performed according to national regulations.

DISCUSSION

(49) 1. Aloj L, Caraco C, Panico M, Zannetti A, Del Vecchio S, Tesauro D, De Luca S, Arra C, Pedone C, Morelli G, Salvatore M. In vitro and in vivo evaluation of 111In-DTPAGlu-G-CCK8 for cholecystokinin-B receptor imaging. J Nucl Med. 2004; 45(3):485-494. 2. Lehenberger S, Barkhausen C, Cohrs S, Fischer E, Grunberg J, Hohn A, Koster U, Schibli R, Turler A, Zhernosekov K. The low-energy beta() and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy. Nucl Med Biol.38(6):917-924.